The present technology relates to a active material used for a secondary battery, an electrode and a secondary battery each of which uses the active material, and a battery pack, an electric vehicle, an electric power storage system, an electric power tool, and an electronic apparatus each of which uses the secondary battery.
Various electronic apparatuses such as mobile phones and personal digital assistants (PDAs) have been widely used, and it has been demanded to further reduce size and weight of the electronic apparatuses and to achieve their longer lives. Accordingly, batteries, in particular, small and light-weight secondary batteries that have ability to achieve high energy density have been developed as power sources for the electronic apparatuses.
Applications of the secondary batteries are not limited to the electronic apparatuses described above, and it has been also considered to apply the secondary batteries to various other applications. Examples of such other applications may include: a battery pack attachably and detachably mounted on, for example, an electronic apparatus; an electric vehicle such as an electric automobile; an electric power storage system such as a home electric power server; and an electric power tool such as an electric drill.
There have been proposed secondary batteries that utilize various charge and discharge principles in order to obtain battery capacity. In particular, attention has been paid to a secondary battery that utilizes insertion and extraction of an electrode reactant and a secondary battery that utilizes precipitation and dissolution of an electrode reactant, which make it possible to achieve higher energy density than other batteries such as a lead-acid battery and a nickel-cadmium battery.
The secondary battery includes an electrode and an electrolytic solution. The electrode includes an active material participating in charge-discharge reaction. The configuration of the active material exerts a large influence on battery characteristics. Accordingly, various studies have been conducted on the configuration of the active material.
More specifically, in order to improve charge-discharge cycle characteristics, a lithium-containing composite oxide represented by Li1+yMO2 (where M is an element such as Ni and Al) is used (for example, refer to PTL 1). In order to suppress gas generation during charge, a complex of a lithium-aluminum oxide represented by LiaAlxOb and lithium-nickel oxide is used (for example, refer to PTL 2). In order to suppress an increase in internal resistance, a lithium transition metal composite oxide represented by LiNixCoyAlzO2 is used (for example, refer to PTL 3). In order to achieve superior cycle characteristics, a lithium composite oxide represented by LixNi1-y-zCoyMnzO2 is used (for example, refer to PTL 4). In order to improve battery characteristics after moisture absorption, an additive represented by LixMyO2 (where M is an element such as Al) is used together with a cathode active material, (for example, refer to PTL 5).